IT-455 Midterm-RegQs
Select the correct statement(s). a. The higher the frequency, the greater the information carrying capacity b. The higher the frequency bandwidth, the greater the information carrying capacity c. Both a and b are correct d. Neither a nor b are correct
c. Both a and b are correct
Select the correct statement(s) regarding Orthogonal Frequency Division Multiplexing (OFDM). a. OFDM is another term for DSSS b. OFDM is the same as FDM, where information channels are separated by guard channels c. OFDM splits the operating spectrum into numerous subcarriers d. All of the above are correct.
c. OFDM splits the operating spectrum into numerous subcarriers
Identify the function(s) of a router. a. provide connectivity between different Layer 2 networks b. provide packet routing to enable end systems to communicate regardless of underlying layer 2 networks c. enable link-to-link routing decisions to be made as the network environment changes d. all are considered router functions
d. all are considered router functions
________________ occurs when an RF wave encounters an object's edge, thus causing secondary waves to be created behind the object. This makes the RF wave "appear" to bend around the object.
diffraction
Free space loss (FSL) is determined by which variables?
frequency, distance
An antenna transmits two signals at 2GHz and 6GHz, to a receive antenna 100km away. Which signal will experience the greatest FSL?
the 6GHz signal will experience greater FSL compared to the 2GHz signal
True or False ARQ (Automatic Repeat Request) is an error control scheme that does not depend upon error detection.
True
True or False M'ary modulation results in an increase in capacity (bps) over symbol rate by enabling symbols to represent more than one logical bit.
True
True or False: 11cos(2π100kHz*t) = 11sin(2π100E3Hz*t + 1.57)
True
True or False: 6cos(20πt + 1.57) = 6cos(2π10t + π/2)
True
True or False: A circuit switched path through a data network ensures that data frames/packets will arrive at the destination in correct sequential order.
True
True or False: A digital signal is susceptible to noise, especially if an amplifier is used which boost both the signal and noise. A repeater eliminates noise by just repeating the signal portion of the digital signal.
True
True or False: A harmonic frequency is an integer multiple of a fundamental frequency.
True
True or False: A signal containing information will be associated with an infinite bandwidth; however most of the signal's energy is contained in the effective bandwidth which can be isolated using a passband RF filter. This is why we call a modulated carrier wave a passband signal.
True
True or False: A signal that represents information will be associated with a fundamental plus harmonic frequencies that can be observed in the frequency domain.
True
True or False: A signal's effective bandwidth is smaller than its absolute bandwidth.
True
True or False: An intranet is a term used for an organizations private IP network.
True
True or False: Analog systems can only use FDM (frequency division multiplexing), not TDM.
True
True or False: Antenna Gain describes the ratio of a directional antenna over that of an isotropic antenna in the desired transmitting direction (i.e., maximum power direction). It is typically represented in the decibel form referenced to the ideal isotropic antenna (i.e., dBi)
True
True or False: Circuit switching can be an inefficient data transfer method between nodes because the physical path is dedicated for the duration of the call even if no data is being transferred.
True
True or False: Digital Systems can use FDM (frequency division multiplexing) or TDM (time division multiplexing).
True
True or False: Digital signals often use analog carrier waves to modulate the digital baseband to a higher frequency.
True
True or False: Doppler spread causes signal performance to change with time due to the movement of mobile users and obstacles.
True
True or False: Error control is based upon the probability of detecting and/or correcting bit errors, and does not guarantee specific error performance (i.e., exact numbers of errors or corrections).
True
True or False: Ethernet (IEEE 802.3) is an example a Data Link Layer 2 LAN protocol.
True
True or False: If we limit a signals frequency bandwidth too narrowly, we introduce signal distortion.
True
True or False: In the time domain, a signal is plotted as a function of time. In the frequency domain, the signal and bandwidth is plotted as a function of Hertz.
True
True or False: Increasing Frequency OR Bandwidth increases data rate(capacity/bps).
True
True or False: Multiple RF signal reflections (e.g., urban environment with many buildings) causes the creation of multiple signal copies that reach the receiver at slightly different times.
True
True or False: Packet size and transmission time are closely related. By breaking the message into smaller packets, overall transmission time decreases. However, breaking the message into packets that are too small eventually increases overhead bits to the point where transmission times begins to increase once again.
True
True or False: Parity checks and Cyclic Redundancy Checks (CRC) are error detection techniques.
True
True or False: Real-time streaming traffic such as live voice and video conferencing, must meet critical delay variation constraints; however, packet loss can sometimes be tolerated.
True
True or False: The Internet Protocol (IPv4) provides end-to-end connectivity between communicating nodes over dissimilar Data Link Layer 2 common networks.
True
True or False: The Shannon Capacity Theorem represents the absolute maximum bit rate capacity possible given signal bandwidth and signal-to-noise ratio (SNR). Any bit rate higher than the Shannon limit is theoretically impossible.
True
True or False: The TCP windowing functions enables network congestion management.
True
True or False: The Virtual Circuit Approach for packet switching networks requires that a preplanned route for packets be established. Therefore, all packets will follow the same path through the network.
True
True or False: The following equation is correct: [N] = [No] + [B] (note: brackets indicate decibel values)
True
True or False: Two common Transport Layer 4 protocols used over an IP network are TCP and UDP.
True
True or False: When determining SNR in decibels, both the received signal power and noise power must be referenced to the same power unit; either 1 watt or 1 milliwatt - e.g., both must be dBW or dBm.
True
True or False: When transmitting packets across a network using the datagram approach, each packet must contain a source and destination address to enable intermediate routing decisions to be made.
True
True or False: Wide area networks (WANs) belong to the Data Link Layer 2 of the OSI Reference Model framework. Frame Relay (FR) and Asynchronous Transfer Mode (ATM) are examples of a WAN; however the Internet is an example of an end-to-end OSI Reference Model, Network Layer 3 protocol.
True
True or False: Wireless systems are unguided and therefore the chance of signal interference is greater than with wired or guided systems. As such, agencies such as the Federal Communications Commission, are required to regulate frequency bandwidth, spectral assignments, and transmission power.
True
True or False: With CDMA, data is combined with a unique pseudorandom number code (PN code), which spreads the signal across a wider frequency spectrum. Both the transmitter and receiver share the same PN code
True
What are the phases of circuit switching?
- Establishment - Exchange - Termination
What is the advantage of using a spread spectrum technique?
- The transmitted signal has better immunity to multipath fading - Transmitted signals are more secure from jamming and eavesdropping - Multiple users can share the same frequency bandwidth
What is the difference between a signal amplifier and signal repeater?
- an amplifier "amplifies" both signal and noise, while a "repeater" only repeats the digital data, and not the noise - repeaters are only used on digital signals, while amplifiers can be used on both analog as well as digital signals
Identify some basic methods used by service providers to enable QoS (quality of service).
- over provisioning - prioritization without guarantees - prioritization with guarantees
True or False For error control block codes, the smaller the Hamming distance between code words, the better the code.
False
True or False: Call setup is required when using packet datagram networks.
False
True or False: Impulse noise is always included as part of the noise floor when determining SNR.
False
True or False: In a packet switched network, two communicating nodes must operate at the same data rates.
False
True or False: In order to communicate with satellites, frequencies below 30MHz must be used in order to penetrate the ionosphere.
False
True or False: In the datagram approach, a call setup between communicating nodes is required prior to the exchange of data.
False
True or False: Optical frequencies are not part of the electromagnetic (EM) spectrum.
False
True or False: Routers are responsible for implementing network reliability functions.
False
True or False: SMTP, HTTP and FTP are the only legal port assignments that can be used with TCP. However, there are additional legal port assignments identified for use with UDP.
False
True or False: Since any device can operate in the industrial, scientific and medical (ISM) frequency bands, FCC frequency licensing is required.
False
True or False: TCP and UDP source and destination ports, which are similar to IP addresses, are used to identify and deliver data segments to the proper network terminal device.
False
Identify an advantage of using packet switching techniques
Line efficiency is higher than when using circuit switching
What is the difference between Nyquist bandwidth capacity and Shannon-Hartley capacity?
Nyquist considers the number of signaling levels per symbol (M), while Shannon-Hartley considers the noise environment
Identify the advantages of the Virtual Circuit Approach
Packets arrive in the correct sequence (i.e., order)
Select the correct statement(s) regarding the TCP protocol. a. TCP is a connection-oriented protocol b. TCP does not guarantee sequential deliver of packets/segments c. TCP must contain both source and destination network addresses d. all statements are correct
a. TCP is a connection-oriented protocol
Regarding wireless transmission, reflections that cause multiple copies of a signal to be received is termed: a. Modulation b. Multipath Fading c. Equalization d. Signal Densification
b. Multipath Fading
Identify the connection-oriented protocol. a. IP b. TCP c. UDP d. All of the above
b. TCP
Which protocol implements flow control? a. IP b. TCP c. UDP d. All of the above
b. TCP
Select the correct statement(s) regarding the UDP protocol. a. UDP is a connection-oriented protocol b. UDP does not guarantee sequential deliver of packets/segments c. UDP must contain both source and destination network addresses d. all statements are correct
b. UDP does not guarantee sequential deliver of packets/segments
Select the correct statement(s) regarding circuit switching. a. circuit switching is a method only used on the public switched telephone network (PSTN) in support of analog voice calls b. circuit establishment is not required prior to exchanging information over a circuit switched connection c. prior to the exchange of information using the circuit switched method, a physical path through the network must be established between communicating nodes d. no statement is correct
c. prior to the exchange of information using the circuit switched method, a physical path through the network must be established between communicating nodes
What is the purpose of the OSI Network Layer? a. provides a control structure for communications between applications b. provides end-to-end error recovery and flow control c. provides upper layers with independence from the data transmission and switching technologies used to connect systems d. concerned with transmission of unstructured bit stream over the physical medium
c. provides upper layers with independence from the data transmission and switching technologies used to connect systems
Select the correct statement(s) regarding frequency hopping spread spectrum (FHSS). a. a PN code is combined with the data to intentionally spread the signal over a wide frequency spectrum b. signals are transmitted at random time intervals c. signals are transmitted over a seemingly random series of frequency channels d. all statements are correct
c. signals are transmitted over a seemingly random series of frequency channels
What is true regarding synchronous TDM? a. With TDM, time slots for each source are transmitted whether or not the source has data to send. This leads to inefficiencies. b. Byte-interleaving is used with synchronous TDM c. Time slots are preassigned to sources d. All are true
d. All are true
Select the correct statement regarding Multipath Propagation: a. The transmitted signal is reflected by obstacles creating multiple copies of the signal with varying delays b. Depending upon differences in path lengths, signals can be reinforced or cancelled as copies are added or subtracted c. In extreme cases, the receiver might only capture reflected signals d. All of the above are correct
d. All of the above are correct
Select the correct statement(s) regarding FDM. a. Guard bands are used to separate frequency channels b. FDM is the only multiplexing method used to combine analog frequency channels c. The bandwidth of the FDM aggregate is equal to the sum of all bandwidth channels plus guard bands d. All of the above are correct
d. All of the above are correct
Select the correct statement(s) regarding packet switching. a. Use of packet technology improves line efficiencies b. Jitter can be experienced caused by packet delay c. Packets do not necessarily follow the same network path d. All statements are correct
d. All statements are correct
Identify the Data Link Layer 2 protocol. a. UDP b. TCP c. IP d. Ethernet
d. Ethernet
Select the correct statement regarding wireless, mobile evolution. a. due to limited spectral availability, better use of allocated spectrum through technology has been a goal to enable greater data capacity b. early cellular systems provided mobile voice calls; however today, users demand mobile access to data networks c. mobile technologies are evolving to enable wireless LAN (WLAN) and personal area networks (WPAN) to work on common smartphone devices d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding Multiple Input, Multiple Output (MIMO) antenna systems. a. multiple antennas are spaced to provide diversity b. data can be transmitted in parallel streams c. enables directionality of the antenna through beam forming d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding antennas. a. an antenna will have the same transmit and receive characteristics when operating at the same frequencies b. the radiation pattern of a directional antenna consists of both a main lobe as well as side lobes c. the beam width of a directional antenna is determined by 3dB power points d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding energy-bit over noise density (Eb/No). a. Eb/No is related to a desired bit error rate (BER) b. Eb/No enables us to determine the capacity (bits per second) achievable in a given system where SNR is known c. the Eb/No equation tells us that an increase in capacity (bps) can be achieved with an increase in receive signal power d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding line-of-sight (LOS) propagation. a. LOS propagation represents the shortest distance between transmitter and receiver. b. although the ionosphere causes signal refraction between earth terminal and satellite, LOS communications can still be accomplished c. LOS is achieved by terrestrial microwave transceivers using directional antennas d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding network switches. a. a switch must have the capability to read source and destination addresses in order to forward data to the correct switch port and network link b. switches play a key role in both LANs and WANs c. switching nodes enable connections to internal/intermediate switching devices as well as to terminal devices d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding signal-to-noise ratio (SNR). a. SNR represents the ratio of signal power over noise power b. "noise" represented in SNR is the noise floor, which is the noise power that exists over a wide frequency range (e.g., thermal noise) c. SNR is unitless even though both signal and noise power are given in watts d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding signals observed in the time and frequency domains. a. signals that contain information typically appear as an aperiodic amplitude signal in the time domain, and will have a bandwidth in the frequency domain b. signals that appear periodic in the time domain (e.g., sinusoidal) will be associated with a single frequency in the frequency domain c. signals containing greater amounts of information will typically have a larger bandwidth in the frequency domain compared to signals containing less information d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding the Internet Protocol (IPv4). a. IPv4 does not guarantee the sequential delivery of datagrams b. IPv4 does not guarantee datagram delivery c. IPv4 is considered a "best effort" network protocol d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding the signal-to-noise ratio (SNR). a. SNR is a unitless ratio b. in decibel form, a negative SNR means that the noise power is greater than the signal power c. the higher the SNR, the better the signal quality d. all statements are correct
d. all statements are correct
Select the correct statement(s) regarding wireless communication limitations. a. wireless communications over free air space is susceptible to interfering signals operating at the same frequency as the communications channel b. since wireless communication channels operate in a shared medium, the careful allocation of frequency channels by regulatory agencies is critical c. direct line-of-sight (LOS) between communicating wireless transceivers is not always required d. all statements are correct
d. all statements are correct
